South Korea conducted live-fire military exercises near its disputed sea border with North Korea yesterday despite Pyongyang's threat to respond with a "merciless" attack.

North Korea did not carry out the threat as it focuses on internal stability two months after the death of its longtime leader Kim Jong-il, and prepares for nuclear-disarmament talks with the United States later this week. But with American forces scheduled to conduct additional military exercises with South Korea over the next few months, tensions are expected to remain high in the region.

Washington and North Korea's neighbours are closely watching how the new leader Kim Jong-un, Kim Jong-il's son, navigates strained ties with South Korea.

The South's manoeuvres took place yesterday in an area of the Yellow Sea that was the target of a North Korean artillery attack in 2010 that killed four South Koreans and raised fears of a wider conflict.

North Korea called the latest exercise a "premeditated military provocation". A North Korean officer said on Sunday that North Koreans would respond to any provocation with "merciless retaliatory strikes". North Korea is prepared for a "total war", and the drills will lead to a "complete collapse" of ties between the Koreas, the North's Committee for the Peaceful Reunification of Korea said in a statement carried yesterday by the official Korean Central News Agency. Such rhetoric has been typical of North Korean media in the past.

North Korea's military was on alert during the drills, which ended after about two hours.